Conventional FinFET transistor structures, also known as lateral FinFETs, have been developed as an alternative to the planar bulk-silicon (bulk-Si) MOSFET structure for improved scalability. FinFETs utilize a Si fin rather than a planar Si surface as the channel/body. A gate electrode straddles the fin. The fin width is the effective body thickness. In the on state, current flows horizontally through the fin from a source to a drain disposed along gated sidewall surfaces of the fin.
In vertical FETs, a source and a drain are disposed on the top and the bottom boundaries of the fin or body. A gate is disposed on either side or all around the fin or the body. In a vertical FET, current flows from the source to the drain vertically through the fin/channel.